On Monday I converted my trusty M&P 40 compact (1.0) to a .357 SIG with my Christmas present Storm Lake barrel, and took it to the range for its first workout. I shot 50 rounds each of American Eagle, Lawman, and SIG Sauer FMJ, as well as 50 rounds of Gold Dot HP. I shot 20 rounds of each brand at 15 and at 20 yards two-handed, and 10 rounds each at 15 yards with my strong hand. Result: the new barrel worked perfectly. When Storm Lake says it’s a drop-in conversion, they aren’t kidding. Even though I’ve shot over 13,000 .40 caliber rounds through my 40c, by the second magazine, I was shooting more accurately at 15 yards with the .357 SIGs than I typically do with the .40s. My long-time accuracy standard is the percentage of my shots I can place into a 4”x4” square. At 15 yards, my typical .40 cal. score is 65%. My first ten .357 shots were low, so I adjusted my aim, and I placed 52 of the remaining 70 15-yard rounds into the square, for a score of 74.5%. Am I happy with that result? You bet! At 20 yards my grouping opened up a bit (OK, a lot!) and my accuracy score fell to 45%, but it wasn’t too horrible, all things considered.
I noticed that the .357’s recoil was much stouter than with the .40, (and stouter than with my larger .357 SIG P320) but it didn’t bother me during two handed shooting. With one-handed shooting, it bothered me a lot! The combination of a powerful round and a small, relatively light gun took a huge toll on my accuracy. I didn’t even bother with the square, I just counted the shots that hit within a 6-inch circle. Only 18 out of 40 did, and many were four to six inches outside of the circle. With one hand, the 40c lurched dramatically low and left. Even when I aimed high and right, some of the shots went low and left anyway. I practice one-handed with all of my guns, which include two .45 acps, the P320 .357 SIG, and the .40, and I haven’t shot that poorly in a long time. Oh, well, just another good excuse for more range time.
Aside from one-handed accuracy, which is on me, the only glitch I experienced was five separate failures to fire with the SIG Sauer ammo. In each case, only a very shallow little dimple appeared on the primer, but the three I reloaded all fired. I kept two of the duds to show to the SIG people in case I encounter more FTFs. At first I thought I’d broken my striker using the higher-powered ammo. My striker is fairly low mileage with about 3,000 rounds on it, so I had to wonder if the 40c was really built to shoot .357 SIG ammo. Fortunately, at that point, I had enough ammo left to check. Following the FTFs, I shot 30 rounds of Gold Dots, and 10 rounds each of the other three brands without any problems. Inspection of this last group’s spent shells (including the SIG Sauers) showed deep, normal firing pin marks. My guess is that the FTFs were due to hard primers on the SIG Sauers. That surprises me because I’ve shot over 1,000 rounds of their ammo in various calibers, and it’s always worked perfectly until now. Obviously, I’ll have to investigate some more. But pinning down the source of those FTFs is another good excuse for more range time.
Getting back to the original purpose of this post, the bottom line is if you’re considering a drop-in barrel for your M&P semi-auto, I can definitely recommend Storm Lake. It looks like a winner.
However, for the time being, I will not make the conversion permanent until I've shot at least 1,000 problem-free .357 SIG rounds. And until I've used up most of my 900 remaining rounds of .40 cal. It looks like plenty o' shootin' ahead! I can live with that.
I’ll update this thread as necessary as I continue my 40c’s .357 SIG adventure.
I noticed that the .357’s recoil was much stouter than with the .40, (and stouter than with my larger .357 SIG P320) but it didn’t bother me during two handed shooting. With one-handed shooting, it bothered me a lot! The combination of a powerful round and a small, relatively light gun took a huge toll on my accuracy. I didn’t even bother with the square, I just counted the shots that hit within a 6-inch circle. Only 18 out of 40 did, and many were four to six inches outside of the circle. With one hand, the 40c lurched dramatically low and left. Even when I aimed high and right, some of the shots went low and left anyway. I practice one-handed with all of my guns, which include two .45 acps, the P320 .357 SIG, and the .40, and I haven’t shot that poorly in a long time. Oh, well, just another good excuse for more range time.
Aside from one-handed accuracy, which is on me, the only glitch I experienced was five separate failures to fire with the SIG Sauer ammo. In each case, only a very shallow little dimple appeared on the primer, but the three I reloaded all fired. I kept two of the duds to show to the SIG people in case I encounter more FTFs. At first I thought I’d broken my striker using the higher-powered ammo. My striker is fairly low mileage with about 3,000 rounds on it, so I had to wonder if the 40c was really built to shoot .357 SIG ammo. Fortunately, at that point, I had enough ammo left to check. Following the FTFs, I shot 30 rounds of Gold Dots, and 10 rounds each of the other three brands without any problems. Inspection of this last group’s spent shells (including the SIG Sauers) showed deep, normal firing pin marks. My guess is that the FTFs were due to hard primers on the SIG Sauers. That surprises me because I’ve shot over 1,000 rounds of their ammo in various calibers, and it’s always worked perfectly until now. Obviously, I’ll have to investigate some more. But pinning down the source of those FTFs is another good excuse for more range time.
Getting back to the original purpose of this post, the bottom line is if you’re considering a drop-in barrel for your M&P semi-auto, I can definitely recommend Storm Lake. It looks like a winner.
However, for the time being, I will not make the conversion permanent until I've shot at least 1,000 problem-free .357 SIG rounds. And until I've used up most of my 900 remaining rounds of .40 cal. It looks like plenty o' shootin' ahead! I can live with that.
I’ll update this thread as necessary as I continue my 40c’s .357 SIG adventure.
